Endometriosis is one of those things you’ve likely heard of but may not know much about. And that’s not your fault; the condition itself is sort of mysterious—even though as many as one in 10 women have it, according to the American College of Obstetricians and Gynecologists, and as the National Institutes of Health reports, anyone who menstruates is at risk. The trouble is, endometriosis presents very differently for different people, which can make it difficult to diagnose in the first place.
Experts also aren’t sure exactly what causes endometriosis, and there isn’t one right way to treat it. So—how do you know if you have endometriosis, what does it feel like, and what can you do? Here’s what we do know.

What is endometriosis, anyway?
Endometriosis is a condition that causes uterine tissueuterine-like tissue to develop outside of the uterus, perhaps on your ovaries or fallopian tubes. Hormone changes during your cycle cause this tissue to thicken and bleed along with your period every month, but since it’s not inside your uterus, it has nowhere to go. This can cause swelling, pain, and internal scarring (caused by inflamed tissue trying to heal). This may sound alarming on paper, but the symptoms can show up differently for everyone—and they aren’t always severe.

What are the symptoms?
That depends. According to the Mayo Clinic, common symptoms include painful periods; pain during sex, urination, or bowel movements; superheavy periods, and bleeding between periods.

Mary Jane Minkin, M.D., a clinical professor in the Department of Obstetrics, Gynecology, and Reproductive Sciences at the Yale University School of Medicine, says that endometriosis pain is really personal and specific to each person who has it. And in her experience, there’s no obvious link between the physical amount of endometrial tissue present in the body, and how intense the pain feels.

“Endometriosis can present with gigantic—I mean basketball-size—cysts on the ovary, and the woman can have zero pain,” Dr. Minkin says. “Then some unfortunate folks have implants of endometriosis that look like cigarette powder burns, and they can have awful pain.”
Another confusing thing about endometriosis, Dr. Minkin says, is that there’s no one specific type of pain associated with it. Stabbing pains, achy pains, period-cramp-like pains, and radiating pains are all possible. So is no pain at all.

Because cysts can grow painlessly, some go undetected until a doctor is examining a patient for other related issues (trouble conceiving or staying pregnant, for example). The National Infertility Association estimates that 40 percent of women with endometriosis will have “some varying degree of infertility.” However, research suggests that while endometriosis can make getting pregnant a little more difficult, it will rarely completely prevent it.

Endometriosis can be hard to diagnose.
Singer-songwriter Halsey said she experienced “years of suffering” before she was diagnosed with endometriosis. In a 2016 tweet, she shared that she spent those years “finding myself doubled over backstage in the middle of my sets, or fighting back tears on an airplane, or even being in so much pain I would vomit or faint.” Halsey recalls doctors’ misdiagnosing her or dismissing her pain, and says that finally being diagnosed was a bittersweet experience. “I wasn’t crazy! I wasn’t a ‘baby!’ I had every right to be feeling like the world was caving in,” she wrote. And her experience is pretty typical.

There are a few reasons for what experts call the diagnosis gap. The first, according to Sandra Gelbard, M.D., an internist and chief medical officer of the Endometriosis Foundation of America, is that many people just don’t know about endometriosis. So they may not be looking for it. Plus, its symptoms can be similar to those of other conditions, like irritable bowel syndrome, a condition called dysmenorrhea (or super-painful periods), polycystic ovary syndrome (PCOS), and more. Because endometriosis can only definitively be diagnosed through a laparoscopy (that’s when you go under general anesthesia so your ob/gyn can look around your pelvis using a fiber-optic camera), doctors may treat other possible conditions first.

Another obstacle to diagnosis, which Halsey touched on, is that health providers may dismiss women’s pain or assume they are overreacting.

New York City psychiatrist Julie Holland, M.D., has seen this happen firsthand. As she previously told Glamour: “Doctors used to tell women they were being hysterical; now the code word is stress.

But by telling a woman she’s just stressed, it negates her entire experience, and unfortunately, this also means doctors don’t get to the root cause.” Because it’s not so clear-cut, a condition like endometriosis can require advocating mightily for oneself, which is especially crucial if you feel your symptoms are being overlooked or underestimated.

How do you treat something so nebulous?
There are two main components to endometriosis treatment: Treating the pain caused by the condition, and addressing the endometriosis tissue itself.

For pain management, over-the-counter medications can help some people. Nonsteroidal anti-inflammatory drugs (NSAIDs) can reduce inflammation and pain, and common painkillers may bring some relief. For other patients, OTC drugs barely touch the pain endometriosis causes, and they may need opioids, a much stronger class of drugs.

Some patients are prescribed supplemental hormones like progesterone, which are thought to work by stopping the growth of endometrial tissue. Birth control pills or patches that suppress your period can also prevent endometriosis tissue from thickening and bleeding along with the uterine lining, which may reduce or even eliminate the pain.

If medication doesn’t work, or patients are trying to get pregnant and can’t use hormones, endometriosis is also treated with surgery, and there are two courses of action here: Patients can have what’s called a conservative surgical procedure, in which a doctor removes endometriosis lesions (though, according to the Cleveland Clinic, endo tissue may grow back). Or in severe cases, sufferers may have a complete hysterectomy — as was the case with Lena Dunham, who recently revealed that she had a hysterectomy at age 31 after battling endometriosis for a decade and undergoing eight prior surgeries.

Bottom line? Trust your gut, and listen to your pain.
If you are at all worried that you might have endometriosis, talk to your gynecologist about your symptoms. It’s important to remember that the condition can affect people differently and that there are multiple options for treatment and pain management. So many things vary when it comes to this condition, there’s no need to assume the worst, and certainly there’s no need to just live with it.